In the conventional storage system, and the computer system comprising the storage system, client information processing apparatus, network, etc., the hardware is initialized by the program including firmware, that is, BIOS, stored in the nonvolatile memory and activates OS (Operating System) at the activation of the circuit board that composes the control unit of the storage system. In the storage system, to update the firmware and make the update effective, the system that uses the firmware must be rebooted. Rebooting the system that uses the firmware, as is obvious, temporarily interrupts the service (process) to the client by the OS operated on the CPU of the circuit board.